Mud degasser



June 14, 1966 B. w. DAWKINS MUD DEGAS S ER Original Filed Nov. 22, 1961WATER ATTO/PA/fVJ United States Patent 3,255,576 MUD DEGASSER Billy W.Dawkins, Houma, La., assignor to United Gas Corporation, Shreveport,La., a corporation of Delaware Continuation of application Ser. No.154,286, Nov. 22,

1961. This application Oct. 2, 1964, Ser. No. 401,269

2 Claims. (Cl. 55192) This application is a continuation of my pendingapplication Serial No. 154,286, filed November 22, 1961, now abandoned.

This invention relates to the degassing of gas-cut mud, and moreparticularly to an apparatus for removing gas from gas-cut mud.

Mud degassers are well known and have been used in instances where thecirculating mud from a well has entrained or dissolved gas therein whichreduces the weight of the mud. As the weight of the mud is carefullycontrolled to in turn control the Well being drilled, gas cuttingpresents a danger of loss of control of the Well and the necessity foreither removing the gas or adding more weight material to bring the mudback up to the desired weight.

Mud degassers used in the past have employed elaborate bafiling in thevacuum chamber to permit release of gas from the mud due to turbulentflow in the presence of a relatively small vacuum. This procedure hasbeen dictated by the lack of an adequate pump for pulling a substantialvacuum on the vacuum chamber. While positive displacement vacuum pumpsfor pulling substantial vacuums are, of course, known, they are veryexpensive and economics does not normally permit their use with muddegassers.

It is an object of this invention to provide a mud degasser whichoperates under a larger vacuum than heretofore possible.

Another object is to provide a mud degasser operating at a greatervacuum than heretofore possible using avery inexpensive pump to pull thevacuum.

Another object is to provide a mud degasser in which an inexpensivecentrifugal pump may be used to remove mud from the vacuum chamber.

Another object is to provide a mud degasser which operates at a greatervacuum than heretofore possible and which provides for operation atvarying degrees of vacuum to accommodate different mud weights in thesame equipment.

Other objects, features and advantages of the invention will be apparentfrom the specification, the drawing and the claims.

In the drawing, wherein an illustrative embodiment is shown,

FIGURE 1 is a view partially in elevation and partially in section of amud degasser constructed in accordance with this invention; and,

FIGURE 2 is a partial plan view of the degasser shown in FIGURE 1.

The mud degasser includes two mud tanks and 11. Mud tank 10 contains themud to be treated and mud tank 11 contains the treated mud. If desired,means may be provided to establish flow between the two tanks to providefor partial recirculation of previously treated mud.

Mud from the well is conveyed to tank 10 through conduit 12. Preferablythe mud is passed through a screen 13 to remove cuttings therefrombefore mud reaches the tank 10. A riser pipe 14 is attached at its lowerend 14a to the mud tank 10 and opens into the mud tank at a level belowthe normal liquid level in tank 10.

Attached to the upper end 14b of the riser 14 is a vacuum chamber 15.Except for the several pipes leading 3,255,576 Patented June 14, 1966ice therefrom, the vacuum chamber 15 is totally enclosed so that it mayoperate at sub-atmospheric pressure. The end 1412 of the riserpreferably terminates in an upwardly facing opening in which there arepositioned bafiies 16 to insure turbulence of the mud at the opening140.

Within the vacuum chamber 15 the mud passes through a relativelyquiescent state as the vacuum chamber .15 is much larger than the riserpipe 14. During this quiescent period additional gas may be releasedfrom the mud.

A mud outlet pipe 17 is attached tothe vacuum chamber below thenormal'mud level therein, and preferably in the bottom thereof, andextends downwardly therefrom to the mud chamber 11. The mud outlet pipe17 has its outlet end 18 provided by the outlet of a pump indicatedgenerally at 19 in mud outlet pipe '17. The outlet 18 of the mud outletpipe is positioned below the normal liquid level in mud tank 11 so thatthe pump 19 will be continuously flooded.

The mud tank 11 is provided with an outlet 21 adjacent its upper endwhich will insure that the mud level in tank 11 is above the outlet 18so that the pump 19 will always be flooded.

A gas pipe 22 is attached to the vacuum chamber at a point above thenormal mud level therein. Preferably the gas pipe is attached at aplurality of points to the top of the vacuum chamber such as at 22a andthrough branch pipe 23 at 23a. The use of the branch pipe 23 permits theuse of a smaller size vacuum chamber.

The gas pipe 22 has a portion 24 of reduced diameter as it proceeds awayfrom the vacuum chamber which is connected to a vacuum pump for drawinga vacuum on the vacuum chamber 15.

The vacuum pump is provided principally by a downwardly extending liquidvacuum pipe 25. This pipe is connected to the gas pipe 24 through amanifold pipe 26 controlled by a valve 27. The lower end of pipe 25 isopen to atmosphere and the pipehas a substantial length up toapproximately forty feet. The length of the pipe will control the extentof the vacuum present in vacuum chamber 15, and it will be found thatthe vacuum in the chamber 15 expressed in inches of mercury will beequal to approximately 1 inch of mercury per foot of pipe 25.

In order to provide water for pipe 25 to permit it to function to pull avacuum in the vacuum chamber, water from any suitable source is providedto manifold 28. If water under pressure is available, such as cityWater, this may be used; or, if desired, the pressure of city water maybe increased, or other water may be delivered to manifold 28 by pump 29.Flow of water to the liquidvacuum pipe 25 is controlled by a valve 31 inmanifold In some instances it may be desirable to pull a lesser vacuum,and for this purpose the length of pipe 25 may be varied, or, forconvenience, a second liquid-vacuum pipe 33 may be provided. This pipeis connected to manifold 26 through a suitable valve 34 and to manifold28 through a suitable valve 35 and a jet 36.

Operation When it is desired to use a degasser, mud returning from thewell is introduced into mud tank 10. The mud level is above the inlet ofriser pipe 14. Tank 11 should be full of mud from the previous use ofthe apparatus, but if not it may be filled in any desired manner withmud so that the outlet of the mud outlet pipe 17 is completely covered.At this time one of the vacuum pumps is started. For instance, ifliquid-vacuum line 25 have a length of 25 feet and it is desired to drawa vacuum in chamber of about 23 to 25 inches of mercury, then valves 27and 31 will be manipulated to use this pump. On the other hand, ifliquid-vacuum pipe 25 .have a length of 17 feet, this pump may be usedto draw a vacuum of about 15 to 17 inches of mercury in vacuum tank 15.The valve controlling water output from manifold 28 is opened and waterpasses through the water jet into the liquid-vacuum pipe. In flowingdown the liquidvacuum pipe, the water induces a vacuum in manifold 26which withdraws the air and gas through gas pipes 24 and 22 from vacuumchamber 15. As the pressure decreases in vacuum chamber 15, mud rises inthe mud riser 14 due to atmospheric pressure exerted on the surface ofthe mud in tank 10. The mud flows up the riser and into the vacuumchamber 15 wherein it continuously gives off its entrained gas. As soonas the chamber has an operative flow of mud therein and the mud outletpipe 17 is filled, the mud outlet pump 19 is started to begin drawingmud from the vacuum chamber 15 and transferring it into the mud storagetank 11. As the level of mud in tank 11 rises, it passes out through theoutlet pipe 21 which is positioned in the nature of an overflow pipefrom whence it is transferred to the circulating mud pits.

From the above explanation it will be appreciated that a veryinexpensive mud degasser has been provided which is extremely versatilein use. As the only power required to operate the vacuum pump is asimple water pump 29 or a source of water under pressure, it is obviousthat an inexpensive water pump can be utilized to draw a much greatervacuum than possible with any positive displacement vacuum pump whichcould economically be used in this type of service. The system lendsitself well to use on land or on water. In fact, over water there is ofcourse a constant supply of salt water which can be delivered to thevacuum pump by the water pump 29 and provide the vacuum at a very lowcost. While water is preferred as the liquid for use in the water pump,it is of course obvious that in an arid region a closed system might beemployed and, if desired, a liquid other than water used.

Inasmuch as a substantial vacuum can be drawn in the vacuum chamber, theneed for extensive baffling within the chamber is done away with. Thisin turn eliminates the need for manholes into the vacuum chamber andperiodic cleaning and replacing of the baffles.

By placing the vacuum chamber above the outlet mud tank and attachingthe outlet mud pipe to the tank below its normal liquid level, the mudtransfer pump 19 will always be flooded. Also, it will be operating withthe aid of the head of mud in outlet line 17, and thus the differentialacross the mud pump 19 will be held to a minimum value.

As noted above, the primary vacuum results from the movement of liquiddown the liquid-vacuum pipe. Thus the jets 32 and 36 could be omitted,but they are desirably employed as they assist in creating the vacuumand they increase the rate at which a vacuum may be induced in thevacuum chamber 15.

The foregoing disclosure and description of the invention isillustrative and explanatory thereof and various changes in the size,shape and materials, as well as in the details of the illustratedconstruction, may be made within the scope of the appended claimswithout departing from the spirit of the invention.

What is claimed is:

1. A mud degasser comprising,

a mud tank,

a riser pipe extending upwardly from the mud tank and having its lowerend open to the interior of the lower section of the tank below a normalmud level therein,

a closed vacuum chamber attached to the upper end of the riser,

a mud outlet pipe attached to the vacuum chamber and extendingdownwardly therefrom,

a pump in the mud outlet pipe for drawing mud from the vacuum chamber,

a second mud tank, said outlet pipe opening into the second mud tankbelow the normal mud level therein,

a gas pipe having its inlet attached to the upper section of the vacuumchamber above a normal mud level therein,

a verticallly extending liquid-vacuum pipe having its lower end open toatmosphere and its upper end connected to and extending downwardly fromthe outlet of said gas pipe,

and means for introducing flowing liquid into the upper section of theliquid-vacuum pipe for downward discharge and flow therein and keepingsaid pipe substantially filled with downflowing liquid.

2. A mud degasser comprising,

a mud tank,

a riser pipe extending upwardly from the mud tank and having its lowerend open to the interior of the lower section of the tank below a normalmud level therein,

a closed vacuum chamber attached to the upper end of the riser,

a mud outlet pipe attached to the vacuum chamber and extendingdownwardly therefrom,

a pump in the mud outlet pipe for drawing mud from the vacuum chamber,

a second mud tank, said mud outlet pipe opening into the second mud tankbelow the normal mud level therein,

a gas pipe having its inlet attached to the upper section of the vacuumchamber above a normal mud level therein,

a vertically extending liquid-vacuum pipe having its lower end open toatmosphere and its upper end connected to and extending downwardly fromthe outlet of said gas pipe,

a jet attached to the upper section of the liquid-vacuum and means forsupplying flowing liquid to the jet for downward discharge and flow insaid liquid-vacuum pipe and keeping said pipe substantially filled withdownflowing liquid.

References Cited by the Examiner UNITED STATES PATENTS 1,777,817 10/1930Whittington 230 2,195,898 4/1940 Newton 55190 2,428,045 8/1947 Sharp eta1. 55-165 2,748,884 6/1956 Erwin 55193 FOREIGN PATENTS 809,430 2/1959Great Britain.

REUBEN FRIEDMAN, Primary Examiner.

C. N HART, Assistant Examiner.

1. A MUD DEGASSER COMPRISING, A MUD TANK, A RISER PIPE EXTENDINGUPWARDLY FROM THE MUD TANK AND HAVING ITS LOWER END OPEN TO THE INTERIOROF THE LOWER SECTION OF THE TANK BELOW A NORMAL MUD LEVEL THEREIN, ACLOSED VACUUM CHAMBER ATTACHED TO THE UPPER END OF THE RISER, A MUDOUTLET PIPE ATTACHED TO THE VACCUM CHAMBER AND EXTENDING DOWNWARDLYTHEREFROM, A PUMP IN THE MUD OUTLET PIPE FOR DRAWING MUD FROM THE VACUUMCHAMBER, A SECOND MUD TANK, SAID OUTLET PIPE OPENING INTO THE SECOND MUDTANK BELOW THE NORMAL MUD LEVEL THEREIN A GAS PIPE HAVING ITS INLETATTACHED TO THE UPPER SECTION OF THE VACCUM CHAMBER ABOVE A NORMAL MUDLEVEL THEREIN, A VERTICALLY EXTENDING LIQUID-VACUUM PIPE HAVING ITSLOWER END OPEN TO ATMOSPHERE AND ITS UPPER END CONNECTED TO THEEXTENDING DOWNWARDLY FROM THE OUTLET OF SAID GAS PIPE, AND MEANS FORINTRODUCING FLOWING LIQUID INTO THE UPPER SECTION OF THE LIQUID-VACUUMPIPE FOR DOWNWARD DISCHARGE AND FLOW THEREIN AND KEEPING SAID PIPESUBSTANTIALLY FILLED WITH DOWNFLOWING LIQUID.